I wish that I did not update my ipad IOS to v13.2.3 while away on a trip. Now I am unable to save my ebook to Dropbox AND unable to open the ebook to my preferred reading app Marvin!

When I try to download an ebook, a pop-up box opens, prompting if I want download or not... yes or no. When I click on yes, it now opens the book on ibooks app.(Previously, there would be options on where to open it ie dropbox, box, bluefire, kindle, marvin). And, When I try to save to dropbox, nothing appears to be saved there. And there is no option at all to open the ebook on Marvin.

Has anyone updated to IOS 13.2.3 ? Do you know how I can open ebook in Marvin? How do I get that option in the list of suggested apps? Also, how do I save ebook to Dropbox?

This has been very frustrating, especially while I am travelling and unable to spend much time trying to figure out the issue. Please help, if you have encountered this issue and were able to resolve it. Thanks.